NH4+ is toxic to plants, inhibit dinitrogenase and also interfere energy metabolism by dissociating ATP formation  from ETC  in both mitochondria and chloroplasts. What will plant cells do to avoid this problem?

a) Plant cells avoid ammonium toxicity by rapidly converting the ammonium generated from nitrate assimilation or photorespiration into nitrate

b) Plant cells avoid ammonium toxicity by rapidly converting the ammonium generated from nitrate assimilation or photorespiration into amino acids

c) The pathway for this conversion involves the sequential actions of glutamine synthetase (GS) and glutamate synthase (GOGAT)

d) The pathway for this conversion involves the sequential actions of Aspartate aminotransferase (Asp-AT) and Asparagine synthetase (AS)

Which of the above statements is incorrect?

#Question id: 2240

#Unit 2. Cellular Organization

 In which of the following cases is energy NOT needed for transmembrane transport?

a. Lysine moves into the cell against its concentration gradient via the Na+/lysine symporter.

b. Potassium ions (K+) move out of the cell down the K+ concentration gradient via potassium channels.

c. Glucose moves into the cell down its concentration gradient via a glucose uniporter.

d. Sodium ions (Na+) move out of the cell down the Na+ concentration gradient via sodium channels.

Which of the following are correct?

#Question id: 2241

#Unit 2. Cellular Organization

Which of the following statement(s) is (are) true of V-class proton pumps?

#Question id: 2242

#Unit 2. Cellular Organization

What two features of the structure of cholesterol make it somewhat amphipathic?

#Question id: 2243

#Unit 2. Cellular Organization

Features of the fluid mosaic model of membrane structure include:

A. a lipid bilayer.

B. dynamic motion of both membrane lipids and proteins.

C. proteins that may either rest on the surface or penetrate the membrane.

D. the hydrophobic core of the bilayer prevents the unassisted movement of water-soluble substances from one side to the other.

E. Covalent interactions between phospholipids, and between phospholipids and proteins, lend strength and resilience to the membrane.

Which of the following is correct?

#Question id: 2244

#Unit 2. Cellular Organization

Arrange the statements below in the proper sequence of events that occur in an action potential:

I. The resting potential is re-established.

II. A stimulus depolarizes the membrane to threshold.

III. Na+ gates open and Na+ rushes into the cell.

IV. K+ gates open and K+ rushes out of the cell.

#Question id: 2245

#Unit 2. Cellular Organization

Which of these statements is generally true of integral membrane proteins?